A knowledge-oriented, context-sensitive architectural framework for service deployment in marginalized rural communities
- Authors: Thinyane, Mamello P
- Date: 2009
- Subjects: Information technology Expert systems (Computer science) Software architecture User interfaces (Computer systems) Ethnoscience Social networks Rural development Technical assistance -- Developing countries Information networks -- Developing countries
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4599 , http://hdl.handle.net/10962/d1004843
- Description: The notion of a global knowledge society is somewhat of a misnomer due to the fact that large portions of the global community are not participants in this global knowledge society which is driven, shaped by and socio-technically biased towards a small fraction of the global population. Information and Communication Technology (ICT) is culture-sensitive and this is a dynamic that is largely ignored in the majority of ICT for Development (ICT4D) interventions, leading to the technological determinism flaw and ultimately a failure of the undertaken projects. The deployment of ICT solutions, in particular in the context of ICT4D, must be informed by the cultural and socio-technical profile of the deployment environments and solutions themselves must be developed with a focus towards context-sensitivity and ethnocentricity. In this thesis, we investigate the viability of a software architectural framework for the development of ICT solutions that are context-sensitive and ethnocentric1, and so aligned with the cultural and social dynamics within the environment of deployment. The conceptual framework, named PIASK, defines five tiers (presentation, interaction, access, social networking, and knowledge base) which allow for: behavioural completeness of the layer components; a modular and functionally decoupled architecture; and the flexibility to situate and contextualize the developed applications along the dimensions of the User Interface (UI), interaction modalities, usage metaphors, underlying Indigenous Knowledge (IK), and access protocols. We have developed a proof-of-concept service platform, called KnowNet, based on the PIASK architecture. KnowNet is built around the knowledge base layer, which consists of domain ontologies that encapsulate the knowledge in the platform, with an intrinsic flexibility to access secondary knowledge repositories. The domain ontologies constructed (as examples) are for the provisioning of eServices to support societal activities (e.g. commerce, health, agriculture, medicine) within a rural and marginalized area of Dwesa, in the Eastern Cape province of South Africa. The social networking layer allows for situating the platform within the local social systems. Heterogeneity of user profiles and multiplicity of end-user devices are handled through the access and the presentation components, and the service logic is implemented by the interaction components. This services platform validates the PIASK architecture for end-to-end provisioning of multi-modal, heterogeneous, ontology-based services. The development of KnowNet was informed on one hand by the latest trends within service architectures, semantic web technologies and social applications, and on the other hand by the context consideration based on the profile (IK systems dynamics, infrastructure, usability requirements) of the Dwesa community. The realization of the service platform is based on the JADE Multi-Agent System (MAS), and this shows the applicability and adequacy of MAS’s for service deployment in a rural context, at the same time providing key advantages such as platform fault-tolerance, robustness and flexibility. While the context of conceptualization of PIASK and the implementation of KnowNet is that of rurality and of ICT4D, the applicability of the architecture extends to other similarly heterogeneous and context-sensitive domains. KnowNet has been validated for functional and technical adequacy, and we have also undertaken an initial prevalidation for social context sensitivity. We observe that the five tier PIASK architecture provides an adequate framework for developing context-sensitive and ethnocentric software: by functionally separating and making explicit the social networking and access tier components, while still maintaining the traditional separation of presentation, business logic and data components.
- Full Text:
- Date Issued: 2009
- Authors: Thinyane, Mamello P
- Date: 2009
- Subjects: Information technology Expert systems (Computer science) Software architecture User interfaces (Computer systems) Ethnoscience Social networks Rural development Technical assistance -- Developing countries Information networks -- Developing countries
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4599 , http://hdl.handle.net/10962/d1004843
- Description: The notion of a global knowledge society is somewhat of a misnomer due to the fact that large portions of the global community are not participants in this global knowledge society which is driven, shaped by and socio-technically biased towards a small fraction of the global population. Information and Communication Technology (ICT) is culture-sensitive and this is a dynamic that is largely ignored in the majority of ICT for Development (ICT4D) interventions, leading to the technological determinism flaw and ultimately a failure of the undertaken projects. The deployment of ICT solutions, in particular in the context of ICT4D, must be informed by the cultural and socio-technical profile of the deployment environments and solutions themselves must be developed with a focus towards context-sensitivity and ethnocentricity. In this thesis, we investigate the viability of a software architectural framework for the development of ICT solutions that are context-sensitive and ethnocentric1, and so aligned with the cultural and social dynamics within the environment of deployment. The conceptual framework, named PIASK, defines five tiers (presentation, interaction, access, social networking, and knowledge base) which allow for: behavioural completeness of the layer components; a modular and functionally decoupled architecture; and the flexibility to situate and contextualize the developed applications along the dimensions of the User Interface (UI), interaction modalities, usage metaphors, underlying Indigenous Knowledge (IK), and access protocols. We have developed a proof-of-concept service platform, called KnowNet, based on the PIASK architecture. KnowNet is built around the knowledge base layer, which consists of domain ontologies that encapsulate the knowledge in the platform, with an intrinsic flexibility to access secondary knowledge repositories. The domain ontologies constructed (as examples) are for the provisioning of eServices to support societal activities (e.g. commerce, health, agriculture, medicine) within a rural and marginalized area of Dwesa, in the Eastern Cape province of South Africa. The social networking layer allows for situating the platform within the local social systems. Heterogeneity of user profiles and multiplicity of end-user devices are handled through the access and the presentation components, and the service logic is implemented by the interaction components. This services platform validates the PIASK architecture for end-to-end provisioning of multi-modal, heterogeneous, ontology-based services. The development of KnowNet was informed on one hand by the latest trends within service architectures, semantic web technologies and social applications, and on the other hand by the context consideration based on the profile (IK systems dynamics, infrastructure, usability requirements) of the Dwesa community. The realization of the service platform is based on the JADE Multi-Agent System (MAS), and this shows the applicability and adequacy of MAS’s for service deployment in a rural context, at the same time providing key advantages such as platform fault-tolerance, robustness and flexibility. While the context of conceptualization of PIASK and the implementation of KnowNet is that of rurality and of ICT4D, the applicability of the architecture extends to other similarly heterogeneous and context-sensitive domains. KnowNet has been validated for functional and technical adequacy, and we have also undertaken an initial prevalidation for social context sensitivity. We observe that the five tier PIASK architecture provides an adequate framework for developing context-sensitive and ethnocentric software: by functionally separating and making explicit the social networking and access tier components, while still maintaining the traditional separation of presentation, business logic and data components.
- Full Text:
- Date Issued: 2009
Selecting and augmenting a FOSS development and deployment environment for personalized video-oriented services in a Telco context
- Authors: Shibeshi, Zelalem Sintayehu
- Date: 2016
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/943 , vital:20005
- Description: The great demand for video services on the Internet is one contributing factor that led telecom companies to search for solutions to deliver innovative video services, using the different access technologies managed by them and leveraging the capacity of enforcing Quality of Service (QoS). One part of the solution was an infrastructure that guarantees QoS for these services, in the form of the IP Multimedia Subsystem (IMS) framework. The IMS framework was developed for delivering innovative multimedia services, but IMS alone does not provide the required services. This has led to further work in the area of multimedia service architectures. One noteworthy architecture is IPTV. IPTV is more than what its name implies, as it allows the development of various innovative video-oriented services and not just tv. When IPTV was introduced, many thought that it would bring back the revenue loss that telecom companies experienced to over-the-top (OTT) service providers. However, despite all its promises, the IPTV implementation has not shown as wide an uptake as one would expect. Although there could be various reasons for the slow penetration of IPTV, one reason could be the technical challenge that IPTV poses to service developers. One of the main reasons for the embarking of the research reported in this thesis was to identify and select free and open source software (FOSS) based platforms and augment them for easy development and deployment of video-oriented services. The thesis motivated how the IPTV architecture, with some modification, can be a good architecture to develop innovative video-oriented services. For a better understanding and investigate the issues of video-oriented service development on different platforms, we followed an incremental and iterative prototyping method. As a result, various video-oriented services were first developed and implementation-related issues were analyzed. This has helped us to identify problems that service developers face, including the requirement to utilize a number of protocols to develop an IPTV-based video-oriented service and the lack of a platform that provides a consistent programming interface to implement them all. The process also helped us to identify new uses cases through the process. As part of our selection process, we found that the Mobicents service development platform can be used as the basis for a good service development and deployment environment for video-oriented services. Mobicents is a Java-based service delivery platform for quick development, deployment and management of next generation network applications. Mobicents is a good choice because it provides a consistent programming interface and supports the various protocols needed in a consistent manner or an easy way to include the support for them. We used Mobicents to compose the environment that developers can use to build video-oriented services. Specifically we developed components and service building blocks that service developer can use to develop various innovative video-oriented services. During our research, we also identified various issues with regard to support from streaming servers in general and open source streaming servers in particular and also with the protocol they use. Specifically, we identified issues with Real Time Streaming Protocol (RTSP), a protocol specified as the media control protocol in the IPTV specification, and made proposals for solving them. We developed an RSTP proxy to augment the features lacking in the current streaming servers and implemented some of the features we proposed in it.
- Full Text:
- Date Issued: 2016
- Authors: Shibeshi, Zelalem Sintayehu
- Date: 2016
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/943 , vital:20005
- Description: The great demand for video services on the Internet is one contributing factor that led telecom companies to search for solutions to deliver innovative video services, using the different access technologies managed by them and leveraging the capacity of enforcing Quality of Service (QoS). One part of the solution was an infrastructure that guarantees QoS for these services, in the form of the IP Multimedia Subsystem (IMS) framework. The IMS framework was developed for delivering innovative multimedia services, but IMS alone does not provide the required services. This has led to further work in the area of multimedia service architectures. One noteworthy architecture is IPTV. IPTV is more than what its name implies, as it allows the development of various innovative video-oriented services and not just tv. When IPTV was introduced, many thought that it would bring back the revenue loss that telecom companies experienced to over-the-top (OTT) service providers. However, despite all its promises, the IPTV implementation has not shown as wide an uptake as one would expect. Although there could be various reasons for the slow penetration of IPTV, one reason could be the technical challenge that IPTV poses to service developers. One of the main reasons for the embarking of the research reported in this thesis was to identify and select free and open source software (FOSS) based platforms and augment them for easy development and deployment of video-oriented services. The thesis motivated how the IPTV architecture, with some modification, can be a good architecture to develop innovative video-oriented services. For a better understanding and investigate the issues of video-oriented service development on different platforms, we followed an incremental and iterative prototyping method. As a result, various video-oriented services were first developed and implementation-related issues were analyzed. This has helped us to identify problems that service developers face, including the requirement to utilize a number of protocols to develop an IPTV-based video-oriented service and the lack of a platform that provides a consistent programming interface to implement them all. The process also helped us to identify new uses cases through the process. As part of our selection process, we found that the Mobicents service development platform can be used as the basis for a good service development and deployment environment for video-oriented services. Mobicents is a Java-based service delivery platform for quick development, deployment and management of next generation network applications. Mobicents is a good choice because it provides a consistent programming interface and supports the various protocols needed in a consistent manner or an easy way to include the support for them. We used Mobicents to compose the environment that developers can use to build video-oriented services. Specifically we developed components and service building blocks that service developer can use to develop various innovative video-oriented services. During our research, we also identified various issues with regard to support from streaming servers in general and open source streaming servers in particular and also with the protocol they use. Specifically, we identified issues with Real Time Streaming Protocol (RTSP), a protocol specified as the media control protocol in the IPTV specification, and made proposals for solving them. We developed an RSTP proxy to augment the features lacking in the current streaming servers and implemented some of the features we proposed in it.
- Full Text:
- Date Issued: 2016
Building IKhwezi, a digital platform to capture everyday Indigenous Knowledge for improving educational outcomes in marginalised communities
- Authors: Ntšekhe, Mathe V K
- Date: 2018
- Subjects: Information technology , Knowledge management , Traditional ecological knowledge , Pedagogical content knowledge , Traditional ecological knowledge -- Technological innovations , IKhwezi , ICT4D , Indigenous Technological Pedagogical Content Knowledge (I-TPACK) , Siyakhula Living Lab
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/62505 , vital:28200
- Description: Aptly captured in the name, the broad mandate of Information and Communications Technologies for Development (ICT4D) is to facilitate the use of Information and Communication Technologies (ICTs) in society to support development. Education, as often stated, is the cornerstone for development, imparting knowledge for conceiving and realising development. In this thesis, we explore how everyday Indigenous Knowledge (IK) can be collected digitally, to enhance the educational outcomes of learners from marginalised backgrounds, by stimulating the production of teaching and learning materials that include the local imagery to have resonance with the learners. As part of the exploration, we reviewed a framework known as Technological Pedagogical Content Knowledge (TPACK), which spells out the different kinds of knowledge needed by teachers to teach effectively with ICTs. In this framework, IK is not present explicitly, but through the concept of context(s). Using Afrocentric and Pan-African scholarship, we argue that this logic is linked to colonialism and a critical decolonising pedagogy necessarily demands explication of IK: to make visible the cultures of the learners in the margins (e.g. Black rural learners). On the strength of this argument, we have proposed that TPACK be augumented to become Indigenous Technological Pedagogical Content Knowledge (I-TPACK). Through this augumentation, I-TPACK becomes an Afrocentric framework for a multicultural education in the digital era. The design of the digital platform for capturing IK relevant for formal education, was done in the Siyakhula Living Lab (SLL). The core idea of a Living Lab (LL) is that users must be understood in the context of their lived everyday reality. Further, they must be involved as co-creators in the design and innovation processes. On a methodological level, the LL environment allowed for the fusing together of multiple methods that can help to create a fitting solution. In this thesis, we followed an iterative user-centred methodology rooted in ethnography and phenomenology. Specifically, through long term conversations and interaction with teachers and ethnographic observations, we conceptualized a platform, IKhwezi, that facilitates the collection of context-sensitive content, collaboratively, and with cost and convenience in mind. We implemented this platform using MediaWiki, based on a number of considerations. From the ICT4D disciplinary point of view, a major consideration was being open to the possibility that other forms of innovation—and, not just ‘technovelty’ (i.e. technological/- technical innovation)—can provide a breakthrough or ingenious solution to the problem at hand. In a sense, we were reinforcing the growing sentiment within the discipline that technology is not the goal, but the means to foregrounding the commonality of the human experience in working towards development. Testing confirmed that there is some value in the platform. This is despite the challenges to onboard users, in pursuit of more content that could bolster the value of everyday IK in improving the educational outcomes of all learners.
- Full Text:
- Date Issued: 2018
- Authors: Ntšekhe, Mathe V K
- Date: 2018
- Subjects: Information technology , Knowledge management , Traditional ecological knowledge , Pedagogical content knowledge , Traditional ecological knowledge -- Technological innovations , IKhwezi , ICT4D , Indigenous Technological Pedagogical Content Knowledge (I-TPACK) , Siyakhula Living Lab
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/62505 , vital:28200
- Description: Aptly captured in the name, the broad mandate of Information and Communications Technologies for Development (ICT4D) is to facilitate the use of Information and Communication Technologies (ICTs) in society to support development. Education, as often stated, is the cornerstone for development, imparting knowledge for conceiving and realising development. In this thesis, we explore how everyday Indigenous Knowledge (IK) can be collected digitally, to enhance the educational outcomes of learners from marginalised backgrounds, by stimulating the production of teaching and learning materials that include the local imagery to have resonance with the learners. As part of the exploration, we reviewed a framework known as Technological Pedagogical Content Knowledge (TPACK), which spells out the different kinds of knowledge needed by teachers to teach effectively with ICTs. In this framework, IK is not present explicitly, but through the concept of context(s). Using Afrocentric and Pan-African scholarship, we argue that this logic is linked to colonialism and a critical decolonising pedagogy necessarily demands explication of IK: to make visible the cultures of the learners in the margins (e.g. Black rural learners). On the strength of this argument, we have proposed that TPACK be augumented to become Indigenous Technological Pedagogical Content Knowledge (I-TPACK). Through this augumentation, I-TPACK becomes an Afrocentric framework for a multicultural education in the digital era. The design of the digital platform for capturing IK relevant for formal education, was done in the Siyakhula Living Lab (SLL). The core idea of a Living Lab (LL) is that users must be understood in the context of their lived everyday reality. Further, they must be involved as co-creators in the design and innovation processes. On a methodological level, the LL environment allowed for the fusing together of multiple methods that can help to create a fitting solution. In this thesis, we followed an iterative user-centred methodology rooted in ethnography and phenomenology. Specifically, through long term conversations and interaction with teachers and ethnographic observations, we conceptualized a platform, IKhwezi, that facilitates the collection of context-sensitive content, collaboratively, and with cost and convenience in mind. We implemented this platform using MediaWiki, based on a number of considerations. From the ICT4D disciplinary point of view, a major consideration was being open to the possibility that other forms of innovation—and, not just ‘technovelty’ (i.e. technological/- technical innovation)—can provide a breakthrough or ingenious solution to the problem at hand. In a sense, we were reinforcing the growing sentiment within the discipline that technology is not the goal, but the means to foregrounding the commonality of the human experience in working towards development. Testing confirmed that there is some value in the platform. This is despite the challenges to onboard users, in pursuit of more content that could bolster the value of everyday IK in improving the educational outcomes of all learners.
- Full Text:
- Date Issued: 2018
A structural and functional specification of a SCIM for service interaction management and personalisation in the IMS
- Authors: Tsietsi, Mosiuoa Jeremia
- Date: 2012
- Subjects: Internet Protocol multimedia subsystem , Internet Protocol multimedia subsystem -- Specifications , Long-Term Evolution (Telecommunications) , European Telecommunications Standards Institute , Wireless communication systems , Multimedia communications
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4606 , http://hdl.handle.net/10962/d1004864 , Internet Protocol multimedia subsystem , Internet Protocol multimedia subsystem -- Specifications , Long-Term Evolution (Telecommunications) , European Telecommunications Standards Institute , Wireless communication systems , Multimedia communications
- Description: The Internet Protocol Multimedia Subsystem (IMS) is a component of the 3G mobile network that has been specified by standards development organisations such as the 3GPP (3rd Generation Partnership Project) and ETSI (European Telecommunication Standards Institute). IMS seeks to guarantee that the telecommunication network of the future provides subscribers with seamless access to services across disparate networks. In order to achieve this, it defines a service architecture that hosts application servers that provide subscribers with value added services. Typically, an application server bundles all the functionality it needs to execute the services it delivers, however this view is currently being challenged. It is now thought that services should be synthesised from simple building blocks called service capabilities. This decomposition would facilitate the re-use of service capabilities across multiple services and would support the creation of new services that could not have originally been conceived. The shift from monolithic services to those built from service capabilities poses a challenge to the current service model in IMS. To accommodate this, the 3GPP has defined an entity known as a service capability interaction manager (SCIM) that would be responsible for managing the interactions between service capabilities in order to realise complex services. Some of these interactions could potentially lead to undesirable results, which the SCIM must work to avoid. As an added requirement, it is believed that the network should allow policies to be applied to network services which the SCIM should be responsible for enforcing. At the time of writing, the functional and structural architecture of the SCIM has not yet been standardised. This thesis explores the current serv ice architecture of the IMS in detail. Proposals that address the structure and functions of the SCIM are carefully compared and contrasted. This investigation leads to the presentation of key aspects of the SCIM, and provides solutions that explain how it should interact with service capabilities, manage undesirable interactions and factor user and network operator policies into its execution model. A modified design of the IMS service layer that embeds the SCIM is subsequently presented and described. The design uses existing IMS protocols and requires no change in the behaviour of the standard IMS entities. In order to develop a testbed for experimental verification of the design, the identification of suitable software platforms was required. This thesis presents some of the most popular platforms currently used by developers such as the Open IMS Core and OpenSER, as well as an open source, Java-based, multimedia communication platform called Mobicents. As a precursor to the development of the SCIM, a converged multimedia service is presented that describes how a video streaming application that is leveraged by a web portal was implemented for an IMS testbed using Mobicents components. The Mobicents SIP Servlets container was subsequently used to model an initial prototype of the SCIM, using a mUlti-component telephony service to illustrate the proposed service execution model. The design focuses on SIP-based services only, but should also work for other types of IMS application servers as well.
- Full Text:
- Date Issued: 2012
- Authors: Tsietsi, Mosiuoa Jeremia
- Date: 2012
- Subjects: Internet Protocol multimedia subsystem , Internet Protocol multimedia subsystem -- Specifications , Long-Term Evolution (Telecommunications) , European Telecommunications Standards Institute , Wireless communication systems , Multimedia communications
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4606 , http://hdl.handle.net/10962/d1004864 , Internet Protocol multimedia subsystem , Internet Protocol multimedia subsystem -- Specifications , Long-Term Evolution (Telecommunications) , European Telecommunications Standards Institute , Wireless communication systems , Multimedia communications
- Description: The Internet Protocol Multimedia Subsystem (IMS) is a component of the 3G mobile network that has been specified by standards development organisations such as the 3GPP (3rd Generation Partnership Project) and ETSI (European Telecommunication Standards Institute). IMS seeks to guarantee that the telecommunication network of the future provides subscribers with seamless access to services across disparate networks. In order to achieve this, it defines a service architecture that hosts application servers that provide subscribers with value added services. Typically, an application server bundles all the functionality it needs to execute the services it delivers, however this view is currently being challenged. It is now thought that services should be synthesised from simple building blocks called service capabilities. This decomposition would facilitate the re-use of service capabilities across multiple services and would support the creation of new services that could not have originally been conceived. The shift from monolithic services to those built from service capabilities poses a challenge to the current service model in IMS. To accommodate this, the 3GPP has defined an entity known as a service capability interaction manager (SCIM) that would be responsible for managing the interactions between service capabilities in order to realise complex services. Some of these interactions could potentially lead to undesirable results, which the SCIM must work to avoid. As an added requirement, it is believed that the network should allow policies to be applied to network services which the SCIM should be responsible for enforcing. At the time of writing, the functional and structural architecture of the SCIM has not yet been standardised. This thesis explores the current serv ice architecture of the IMS in detail. Proposals that address the structure and functions of the SCIM are carefully compared and contrasted. This investigation leads to the presentation of key aspects of the SCIM, and provides solutions that explain how it should interact with service capabilities, manage undesirable interactions and factor user and network operator policies into its execution model. A modified design of the IMS service layer that embeds the SCIM is subsequently presented and described. The design uses existing IMS protocols and requires no change in the behaviour of the standard IMS entities. In order to develop a testbed for experimental verification of the design, the identification of suitable software platforms was required. This thesis presents some of the most popular platforms currently used by developers such as the Open IMS Core and OpenSER, as well as an open source, Java-based, multimedia communication platform called Mobicents. As a precursor to the development of the SCIM, a converged multimedia service is presented that describes how a video streaming application that is leveraged by a web portal was implemented for an IMS testbed using Mobicents components. The Mobicents SIP Servlets container was subsequently used to model an initial prototype of the SCIM, using a mUlti-component telephony service to illustrate the proposed service execution model. The design focuses on SIP-based services only, but should also work for other types of IMS application servers as well.
- Full Text:
- Date Issued: 2012
Transcription factor binding specificity and occupancy : elucidation, modelling and evaluation
- Authors: Kibet, Caleb Kipkurui
- Date: 2017
- Subjects: Transcription factors , Transcription factors -- Data processing , Motif Assessment and Ranking Suite
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:21185 , http://hdl.handle.net/10962/6838
- Description: The major contributions of this thesis are addressing the need for an objective quality evaluation of a transcription factor binding model, demonstrating the value of the tools developed to this end and elucidating how in vitro and in vivo information can be utilized to improve TF binding specificity models. Accurate elucidation of TF binding specificity remains an ongoing challenge in gene regulatory research. Several in vitro and in vivo experimental techniques have been developed followed by a proliferation of algorithms, and ultimately, the binding models. This increase led to a choice problem for the end users: which tools to use, and which is the most accurate model for a given TF? Therefore, the first section of this thesis investigates the motif assessment problem: how scoring functions, choice and processing of benchmark data, and statistics used in evaluation affect motif ranking. This analysis revealed that TF motif quality assessment requires a systematic comparative analysis, and that scoring functions used have a TF-specific effect on motif ranking. These results advised the design of a Motif Assessment and Ranking Suite MARS, supported by PBM and ChIP-seq benchmark data and an extensive collection of PWM motifs. MARS implements consistency, enrichment, and scoring and classification-based motif evaluation algorithms. Transcription factor binding is also influenced and determined by contextual factors: chromatin accessibility, competition or cooperation with other TFs, cell line or condition specificity, binding locality (e.g. proximity to transcription start sites) and the shape of the binding site (DNA-shape). In vitro techniques do not capture such context; therefore, this thesis also combines PBM and DNase-seq data using a comparative k-mer enrichment approach that compares open chromatin with genome-wide prevalence, achieving a modest performance improvement when benchmarked on ChIP-seq data. Finally, since statistical and probabilistic methods cannot capture all the information that determine binding, a machine learning approach (XGBooost) was implemented to investigate how the features contribute to TF specificity and occupancy. This combinatorial approach improves the predictive ability of TF specificity models with the most predictive feature being chromatin accessibility, while the DNA-shape and conservation information all significantly improve on the baseline model of k-mer and DNase data. The results and the tools introduced in this thesis are useful for systematic comparative analysis (via MARS) and a combinatorial approach to modelling TF binding specificity, including appropriate feature engineering practices for machine learning modelling.
- Full Text:
- Date Issued: 2017
- Authors: Kibet, Caleb Kipkurui
- Date: 2017
- Subjects: Transcription factors , Transcription factors -- Data processing , Motif Assessment and Ranking Suite
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:21185 , http://hdl.handle.net/10962/6838
- Description: The major contributions of this thesis are addressing the need for an objective quality evaluation of a transcription factor binding model, demonstrating the value of the tools developed to this end and elucidating how in vitro and in vivo information can be utilized to improve TF binding specificity models. Accurate elucidation of TF binding specificity remains an ongoing challenge in gene regulatory research. Several in vitro and in vivo experimental techniques have been developed followed by a proliferation of algorithms, and ultimately, the binding models. This increase led to a choice problem for the end users: which tools to use, and which is the most accurate model for a given TF? Therefore, the first section of this thesis investigates the motif assessment problem: how scoring functions, choice and processing of benchmark data, and statistics used in evaluation affect motif ranking. This analysis revealed that TF motif quality assessment requires a systematic comparative analysis, and that scoring functions used have a TF-specific effect on motif ranking. These results advised the design of a Motif Assessment and Ranking Suite MARS, supported by PBM and ChIP-seq benchmark data and an extensive collection of PWM motifs. MARS implements consistency, enrichment, and scoring and classification-based motif evaluation algorithms. Transcription factor binding is also influenced and determined by contextual factors: chromatin accessibility, competition or cooperation with other TFs, cell line or condition specificity, binding locality (e.g. proximity to transcription start sites) and the shape of the binding site (DNA-shape). In vitro techniques do not capture such context; therefore, this thesis also combines PBM and DNase-seq data using a comparative k-mer enrichment approach that compares open chromatin with genome-wide prevalence, achieving a modest performance improvement when benchmarked on ChIP-seq data. Finally, since statistical and probabilistic methods cannot capture all the information that determine binding, a machine learning approach (XGBooost) was implemented to investigate how the features contribute to TF specificity and occupancy. This combinatorial approach improves the predictive ability of TF specificity models with the most predictive feature being chromatin accessibility, while the DNA-shape and conservation information all significantly improve on the baseline model of k-mer and DNase data. The results and the tools introduced in this thesis are useful for systematic comparative analysis (via MARS) and a combinatorial approach to modelling TF binding specificity, including appropriate feature engineering practices for machine learning modelling.
- Full Text:
- Date Issued: 2017
Interrupt-generating active data objects
- Authors: Clayton, Peter Graham
- Date: 1990
- Subjects: Parallel programming (Computer science) Electronic data processing -- Distributed processing
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4677 , http://hdl.handle.net/10962/d1006700
- Description: An investigation is presented into an interrupt-generating object model which is designed to reduce the effort of programming distributed memory multicomputer networks. The object model is aimed at the natural modelling of problem domains in which a number of concurrent entities interrupt one another as they lay claim to shared resources. The proposed computational model provides for the safe encapsulation of shared data, and incorporates inherent arbitration for simultaneous access to the data. It supplies a predicate triggering mechanism for use in conditional synchronization and as an alternative mechanism to polling. Linguistic support for the proposal requires a novel form of control structure which is able to interface sensibly with interrupt-generating active data objects. The thesis presents the proposal as an elemental language structure, with axiomatic guarantees which enforce safety properties and aid in program proving. The established theory of CSP is used to reason about the object model and its interface. An overview is presented of a programming language called HUL, whose semantics reflect the proposed computational model. Using the syntax of HUL, the application of the interrupt-generating active data object is illustrated. A range of standard concurrent problems is presented to demonstrate the properties of the interrupt-generating computational model. Furthermore, the thesis discusses implementation considerations which enable the model to be mapped precisely onto multicomputer networks, and which sustain the abstract programming level provided by the interrupt-generating active data object in the wider programming structures of HUL.
- Full Text:
- Date Issued: 1990
- Authors: Clayton, Peter Graham
- Date: 1990
- Subjects: Parallel programming (Computer science) Electronic data processing -- Distributed processing
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4677 , http://hdl.handle.net/10962/d1006700
- Description: An investigation is presented into an interrupt-generating object model which is designed to reduce the effort of programming distributed memory multicomputer networks. The object model is aimed at the natural modelling of problem domains in which a number of concurrent entities interrupt one another as they lay claim to shared resources. The proposed computational model provides for the safe encapsulation of shared data, and incorporates inherent arbitration for simultaneous access to the data. It supplies a predicate triggering mechanism for use in conditional synchronization and as an alternative mechanism to polling. Linguistic support for the proposal requires a novel form of control structure which is able to interface sensibly with interrupt-generating active data objects. The thesis presents the proposal as an elemental language structure, with axiomatic guarantees which enforce safety properties and aid in program proving. The established theory of CSP is used to reason about the object model and its interface. An overview is presented of a programming language called HUL, whose semantics reflect the proposed computational model. Using the syntax of HUL, the application of the interrupt-generating active data object is illustrated. A range of standard concurrent problems is presented to demonstrate the properties of the interrupt-generating computational model. Furthermore, the thesis discusses implementation considerations which enable the model to be mapped precisely onto multicomputer networks, and which sustain the abstract programming level provided by the interrupt-generating active data object in the wider programming structures of HUL.
- Full Text:
- Date Issued: 1990
RADGIS - an improved architecture for runtime-extensible, distributed GIS applications
- Authors: Preston, Richard Michael
- Date: 2002
- Subjects: Geographic information systems
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4626 , http://hdl.handle.net/10962/d1006497
- Description: A number of GIS architectures and technologies have emerged recently to facilitate the visualisation and processing of geospatial data over the Web. The work presented in this dissertation builds on these efforts and undertakes to overcome some of the major problems with traditional GIS client architectures, including application bloat, lack of customisability, and lack of interoperability between GIS products. In this dissertation we describe how a new client-side GIS architecture was developed and implemented as a proof-of-concept application called RADGIS, which is based on open standards and emerging distributed component-based software paradigms. RADGIS reflects the current trend in development focus from Web browser-based applications to customised clients, based on open standards, that make use of distributed Web services. While much attention has been paid to exposing data on the Web, there is growing momentum towards providing “value-added” services. A good example of this is the tremendous industry interest in the provision of location-based services, which has been discussed as a special use-case of our RADGIS architecture. Thus, in the near future client applications will not simply be used to access data transparently, but will also become facilitators for the location-transparent invocation of local and remote services. This flexible architecture will ensure that data can be stored and processed independently of the location of the client that wishes to view or interact with it. Our RADGIS application enables content developers and end-users to create and/or customise GIS applications dynamically at runtime through the incorporation of GIS services. This ensures that the client application has the flexibility to withstand changing levels of expertise or user requirements. These GIS services are implemented as components that execute locally on the client machine, or as remote CORBA Objects or EJBs. Assembly and deployment of these components is achieved using a specialised XML descriptor. This XML descriptor is written using a markup language that we developed specifically for this purpose, called DGCML, which contains deployment information, as well as a GUI specification and links to an XML-based help system that can be merged with the RADGIS client application’s existing help system. Thus, no additional requirements are imposed on object developers by the RADGIS architecture, i.e. there is no need to rewrite existing objects since DGCML acts as a runtime-customisable wrapper, allowing existing objects to be utilised by RADGIS. While the focus of this thesis has been on overcoming the above-mentioned problems with traditional GIS applications, the work described here can also be applied in a much broader context, especially in the development of highly customisable client applications that are able to integrate Web services at runtime.
- Full Text:
- Date Issued: 2002
- Authors: Preston, Richard Michael
- Date: 2002
- Subjects: Geographic information systems
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4626 , http://hdl.handle.net/10962/d1006497
- Description: A number of GIS architectures and technologies have emerged recently to facilitate the visualisation and processing of geospatial data over the Web. The work presented in this dissertation builds on these efforts and undertakes to overcome some of the major problems with traditional GIS client architectures, including application bloat, lack of customisability, and lack of interoperability between GIS products. In this dissertation we describe how a new client-side GIS architecture was developed and implemented as a proof-of-concept application called RADGIS, which is based on open standards and emerging distributed component-based software paradigms. RADGIS reflects the current trend in development focus from Web browser-based applications to customised clients, based on open standards, that make use of distributed Web services. While much attention has been paid to exposing data on the Web, there is growing momentum towards providing “value-added” services. A good example of this is the tremendous industry interest in the provision of location-based services, which has been discussed as a special use-case of our RADGIS architecture. Thus, in the near future client applications will not simply be used to access data transparently, but will also become facilitators for the location-transparent invocation of local and remote services. This flexible architecture will ensure that data can be stored and processed independently of the location of the client that wishes to view or interact with it. Our RADGIS application enables content developers and end-users to create and/or customise GIS applications dynamically at runtime through the incorporation of GIS services. This ensures that the client application has the flexibility to withstand changing levels of expertise or user requirements. These GIS services are implemented as components that execute locally on the client machine, or as remote CORBA Objects or EJBs. Assembly and deployment of these components is achieved using a specialised XML descriptor. This XML descriptor is written using a markup language that we developed specifically for this purpose, called DGCML, which contains deployment information, as well as a GUI specification and links to an XML-based help system that can be merged with the RADGIS client application’s existing help system. Thus, no additional requirements are imposed on object developers by the RADGIS architecture, i.e. there is no need to rewrite existing objects since DGCML acts as a runtime-customisable wrapper, allowing existing objects to be utilised by RADGIS. While the focus of this thesis has been on overcoming the above-mentioned problems with traditional GIS applications, the work described here can also be applied in a much broader context, especially in the development of highly customisable client applications that are able to integrate Web services at runtime.
- Full Text:
- Date Issued: 2002
A formalised ontology for network attack classification
- Authors: Van Heerden, Renier Pelser
- Date: 2014
- Subjects: Computer networks -- Security measures Computer security Computer crimes -- Investigation Computer crimes -- Prevention
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4691 , http://hdl.handle.net/10962/d1011603
- Description: One of the most popular attack vectors against computers are their network connections. Attacks on computers through their networks are commonplace and have various levels of complexity. This research formally describes network-based computer attacks in the form of a story, formally and within an ontology. The ontology categorises network attacks where attack scenarios are the focal class. This class consists of: Denial-of- Service, Industrial Espionage, Web Defacement, Unauthorised Data Access, Financial Theft, Industrial Sabotage, Cyber-Warfare, Resource Theft, System Compromise, and Runaway Malware. This ontology was developed by building a taxonomy and a temporal network attack model. Network attack instances (also know as individuals) are classified according to their respective attack scenarios, with the use of an automated reasoner within the ontology. The automated reasoner deductions are verified formally; and via the automated reasoner, a relaxed set of scenarios is determined, which is relevant in a near real-time environment. A prototype system (called Aeneas) was developed to classify network-based attacks. Aeneas integrates the sensors into a detection system that can classify network attacks in a near real-time environment. To verify the ontology and the prototype Aeneas, a virtual test bed was developed in which network-based attacks were generated to verify the detection system. Aeneas was able to detect incoming attacks and classify them according to their scenario. The novel part of this research is the attack scenarios that are described in the form of a story, as well as formally and in an ontology. The ontology is used in a novel way to determine to which class attack instances belong and how the network attack ontology is affected in a near real-time environment.
- Full Text:
- Date Issued: 2014
- Authors: Van Heerden, Renier Pelser
- Date: 2014
- Subjects: Computer networks -- Security measures Computer security Computer crimes -- Investigation Computer crimes -- Prevention
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4691 , http://hdl.handle.net/10962/d1011603
- Description: One of the most popular attack vectors against computers are their network connections. Attacks on computers through their networks are commonplace and have various levels of complexity. This research formally describes network-based computer attacks in the form of a story, formally and within an ontology. The ontology categorises network attacks where attack scenarios are the focal class. This class consists of: Denial-of- Service, Industrial Espionage, Web Defacement, Unauthorised Data Access, Financial Theft, Industrial Sabotage, Cyber-Warfare, Resource Theft, System Compromise, and Runaway Malware. This ontology was developed by building a taxonomy and a temporal network attack model. Network attack instances (also know as individuals) are classified according to their respective attack scenarios, with the use of an automated reasoner within the ontology. The automated reasoner deductions are verified formally; and via the automated reasoner, a relaxed set of scenarios is determined, which is relevant in a near real-time environment. A prototype system (called Aeneas) was developed to classify network-based attacks. Aeneas integrates the sensors into a detection system that can classify network attacks in a near real-time environment. To verify the ontology and the prototype Aeneas, a virtual test bed was developed in which network-based attacks were generated to verify the detection system. Aeneas was able to detect incoming attacks and classify them according to their scenario. The novel part of this research is the attack scenarios that are described in the form of a story, as well as formally and in an ontology. The ontology is used in a novel way to determine to which class attack instances belong and how the network attack ontology is affected in a near real-time environment.
- Full Text:
- Date Issued: 2014
Pro-active visualization of cyber security on a National Level : a South African case study
- Authors: Swart, Ignatius Petrus
- Date: 2015
- Subjects: Internet -- Security measures -- South Africa , Computer security -- Government policy -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4718 , http://hdl.handle.net/10962/d1017940
- Description: The need for increased national cyber security situational awareness is evident from the growing number of published national cyber security strategies. Governments are progressively seen as responsible for cyber security, but at the same time increasingly constrained by legal, privacy and resource considerations. Infrastructure and services that form part of the national cyber domain are often not under the control of government, necessitating the need for information sharing between governments and commercial partners. While sharing of security information is necessary, it typically requires considerable time to be implemented effectively. In an effort to decrease the time and effort required for cyber security situational awareness, this study considered commercially available data sources relating to a national cyber domain. Open source information is typically used by attackers to gather information with great success. An understanding of the data provided by these sources can also afford decision makers the opportunity to set priorities more effectively. Through the use of an adapted Joint Directors of Laboratories (JDL) fusion model, an experimental system was implemented that visualized the potential that open source intelligence could have on cyber situational awareness. Datasets used in the validation of the model contained information obtained from eight different data sources over a two year period with a focus on the South African .co.za sub domain. Over a million infrastructure devices were examined in this study along with information pertaining to a potential 88 million vulnerabilities on these devices. During the examination of data sources, a severe lack of information regarding the human aspect in cyber security was identified that led to the creation of a novel Personally Identifiable Information detection sensor (PII). The resultant two million records pertaining to PII in the South African domain were incorporated into the data fusion experiment for processing. The results of this processing are discussed in the three case studies. The results offered in this study aim to highlight how data fusion and effective visualization can serve to move national cyber security from a primarily reactive undertaking to a more pro-active model.
- Full Text:
- Date Issued: 2015
- Authors: Swart, Ignatius Petrus
- Date: 2015
- Subjects: Internet -- Security measures -- South Africa , Computer security -- Government policy -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4718 , http://hdl.handle.net/10962/d1017940
- Description: The need for increased national cyber security situational awareness is evident from the growing number of published national cyber security strategies. Governments are progressively seen as responsible for cyber security, but at the same time increasingly constrained by legal, privacy and resource considerations. Infrastructure and services that form part of the national cyber domain are often not under the control of government, necessitating the need for information sharing between governments and commercial partners. While sharing of security information is necessary, it typically requires considerable time to be implemented effectively. In an effort to decrease the time and effort required for cyber security situational awareness, this study considered commercially available data sources relating to a national cyber domain. Open source information is typically used by attackers to gather information with great success. An understanding of the data provided by these sources can also afford decision makers the opportunity to set priorities more effectively. Through the use of an adapted Joint Directors of Laboratories (JDL) fusion model, an experimental system was implemented that visualized the potential that open source intelligence could have on cyber situational awareness. Datasets used in the validation of the model contained information obtained from eight different data sources over a two year period with a focus on the South African .co.za sub domain. Over a million infrastructure devices were examined in this study along with information pertaining to a potential 88 million vulnerabilities on these devices. During the examination of data sources, a severe lack of information regarding the human aspect in cyber security was identified that led to the creation of a novel Personally Identifiable Information detection sensor (PII). The resultant two million records pertaining to PII in the South African domain were incorporated into the data fusion experiment for processing. The results of this processing are discussed in the three case studies. The results offered in this study aim to highlight how data fusion and effective visualization can serve to move national cyber security from a primarily reactive undertaking to a more pro-active model.
- Full Text:
- Date Issued: 2015
An investigation into the control of audio streaming across networks having diverse quality of service mechanisms
- Authors: Foulkes, Philip James
- Date: 2012
- Subjects: Streaming audio -- Testing Data transmission systems -- Testing Computer networks -- Management Computer networks -- Evaluation Computer network protocols -- Standards
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4607 , http://hdl.handle.net/10962/d1004865
- Description: The transmission of realtime audio data across digital networks is subject to strict quality of service requirements. These networks need to be able to guarantee network resources (e.g., bandwidth), ensure timely and deterministic data delivery, and provide time synchronisation mechanisms to ensure successful transmission of this data. Two open standards-based networking technologies, namely IEEE 1394 and the recently standardised Ethernet AVB, provide distinct methods for achieving these goals. Audio devices that are compatible with IEEE 1394 networks exist, and audio devices that are compatible with Ethernet AVB networks are starting to come onto the market. There is a need for mechanisms to provide compatibility between the audio devices that reside on these disparate networks such that existing IEEE 1394 audio devices are able to communicate with Ethernet AVB audio devices, and vice versa. The audio devices that reside on these networks may be remotely controlled by a diverse set of incompatible command and control protocols. It is desirable to have a common network-neutral method of control over the various parameters of the devices that reside on these networks. As part of this study, two Ethernet AVB systems were developed. One system acts as an Ethernet AVB audio endpoint device and another system acts as an audio gateway between IEEE 1394 and Ethernet AVB networks. These systems, along with existing IEEE 1394 audio devices, were used to demonstrate the ability to transfer audio data between the networking technologies. Each of the devices is remotely controllable via a network neutral command and control protocol, XFN. The IEEE 1394 and Ethernet AVB devices are used to demonstrate the use of the XFN protocol to allow for network neutral connection management to take place between IEEE 1394 and Ethernet AVB networks. User control over these diverse devices is achieved via the use of a graphical patchbay application, which aims to provide a consistent user interface to a diverse range of devices.
- Full Text:
- Date Issued: 2012
- Authors: Foulkes, Philip James
- Date: 2012
- Subjects: Streaming audio -- Testing Data transmission systems -- Testing Computer networks -- Management Computer networks -- Evaluation Computer network protocols -- Standards
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4607 , http://hdl.handle.net/10962/d1004865
- Description: The transmission of realtime audio data across digital networks is subject to strict quality of service requirements. These networks need to be able to guarantee network resources (e.g., bandwidth), ensure timely and deterministic data delivery, and provide time synchronisation mechanisms to ensure successful transmission of this data. Two open standards-based networking technologies, namely IEEE 1394 and the recently standardised Ethernet AVB, provide distinct methods for achieving these goals. Audio devices that are compatible with IEEE 1394 networks exist, and audio devices that are compatible with Ethernet AVB networks are starting to come onto the market. There is a need for mechanisms to provide compatibility between the audio devices that reside on these disparate networks such that existing IEEE 1394 audio devices are able to communicate with Ethernet AVB audio devices, and vice versa. The audio devices that reside on these networks may be remotely controlled by a diverse set of incompatible command and control protocols. It is desirable to have a common network-neutral method of control over the various parameters of the devices that reside on these networks. As part of this study, two Ethernet AVB systems were developed. One system acts as an Ethernet AVB audio endpoint device and another system acts as an audio gateway between IEEE 1394 and Ethernet AVB networks. These systems, along with existing IEEE 1394 audio devices, were used to demonstrate the ability to transfer audio data between the networking technologies. Each of the devices is remotely controllable via a network neutral command and control protocol, XFN. The IEEE 1394 and Ethernet AVB devices are used to demonstrate the use of the XFN protocol to allow for network neutral connection management to take place between IEEE 1394 and Ethernet AVB networks. User control over these diverse devices is achieved via the use of a graphical patchbay application, which aims to provide a consistent user interface to a diverse range of devices.
- Full Text:
- Date Issued: 2012
Transformative ICT education practices in rural secondary schools for developmental needs and realities: the Eastern Cape Province, South Africa
- Authors: Simuja, Clement
- Date: 2020
- Subjects: Education, Secondary -- South Africa -- Data processing , Information technology -- Study and teaching (Secondary) --South Africa , Educational technology -- Developing countries , Rural development -- Developing countries , Computer-assisted instruction -- South Africa -- Eastern Cape , Internet in education -- South Africa , Rural schools -- South Africa -- Eastern Cape , Community and school -- South Africa -- Eastern Cape
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/150631 , vital:38991
- Description: The perceived social development significance of Information and Communication Technology (ICT) has dramatically expanded the domains in which this cluster of ICTs is being discussed and acted upon. The action to promote community development in rural areas in South Africa has made its way into the introduction of ICT education in secondary schools. Since rural secondary schools form part of the framework for rural communities, they are being challenged to provide ICT education that makes a difference in learners’ lives. This requires engaging education practices that inspire learners to construct knowledge of ICT that does not only respond to examination purposes but rather, to the needs and development aspirations of the community. This research examines the experience of engaging learners and communities in socially informed ICT education in rural secondary schools. Specifically, it seeks to develop a critique of current practices involved in ICT education in rural secondary schools, and explores plausible alternatives to such practices that would make ICT education more transformative and structured towards the developmental concerns of communities. The main empirical focus for the research was five rural secondary schools in the Eastern Cape Province in South Africa. The research involved 53 participants that participated in a socially informed ICT training process. The training was designed to inspire participants to share their self-defined ICT education and ICT knowledge experiences. Critical Action Learning and Philosophical Inquiry provided the methodological framework, whilst the theoretical framework draws on Foucault’s philosophical ideas on power-knowledge relations. Through this theoretical analysis, the research examines the dynamic interplay of practices in ICT education with the values, ideals, and knowledge that form the core-life experiences of learners and rural communities. The research findings of this study indicate that current ICT education practices in rural secondary schools are endowed with ideologies that are affecting learners’ identity, social experiences, power, and ownership of the reflective meaning of using ICTs in community development. The contribution of this thesis lies in demonstrating ways that reframe ICT education transformatively, and more specifically its practices in the light of the way power, identity, ownership and social experience construct and offer learners a transformative view of self and the world. This could enable ICT education to fulfil the potential of contributing to social development in rural communities. The thesis culminates by presenting a theoretical framework that articulates the structural and authoritative components of ICT education practices – these relate to learners’ conscious understandings and represented thoughts, sensations and meanings embedded in the context, and actions and locations of using their knowledge of ICT.
- Full Text:
- Date Issued: 2020
- Authors: Simuja, Clement
- Date: 2020
- Subjects: Education, Secondary -- South Africa -- Data processing , Information technology -- Study and teaching (Secondary) --South Africa , Educational technology -- Developing countries , Rural development -- Developing countries , Computer-assisted instruction -- South Africa -- Eastern Cape , Internet in education -- South Africa , Rural schools -- South Africa -- Eastern Cape , Community and school -- South Africa -- Eastern Cape
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/150631 , vital:38991
- Description: The perceived social development significance of Information and Communication Technology (ICT) has dramatically expanded the domains in which this cluster of ICTs is being discussed and acted upon. The action to promote community development in rural areas in South Africa has made its way into the introduction of ICT education in secondary schools. Since rural secondary schools form part of the framework for rural communities, they are being challenged to provide ICT education that makes a difference in learners’ lives. This requires engaging education practices that inspire learners to construct knowledge of ICT that does not only respond to examination purposes but rather, to the needs and development aspirations of the community. This research examines the experience of engaging learners and communities in socially informed ICT education in rural secondary schools. Specifically, it seeks to develop a critique of current practices involved in ICT education in rural secondary schools, and explores plausible alternatives to such practices that would make ICT education more transformative and structured towards the developmental concerns of communities. The main empirical focus for the research was five rural secondary schools in the Eastern Cape Province in South Africa. The research involved 53 participants that participated in a socially informed ICT training process. The training was designed to inspire participants to share their self-defined ICT education and ICT knowledge experiences. Critical Action Learning and Philosophical Inquiry provided the methodological framework, whilst the theoretical framework draws on Foucault’s philosophical ideas on power-knowledge relations. Through this theoretical analysis, the research examines the dynamic interplay of practices in ICT education with the values, ideals, and knowledge that form the core-life experiences of learners and rural communities. The research findings of this study indicate that current ICT education practices in rural secondary schools are endowed with ideologies that are affecting learners’ identity, social experiences, power, and ownership of the reflective meaning of using ICTs in community development. The contribution of this thesis lies in demonstrating ways that reframe ICT education transformatively, and more specifically its practices in the light of the way power, identity, ownership and social experience construct and offer learners a transformative view of self and the world. This could enable ICT education to fulfil the potential of contributing to social development in rural communities. The thesis culminates by presenting a theoretical framework that articulates the structural and authoritative components of ICT education practices – these relate to learners’ conscious understandings and represented thoughts, sensations and meanings embedded in the context, and actions and locations of using their knowledge of ICT.
- Full Text:
- Date Issued: 2020
A multi-threading software countermeasure to mitigate side channel analysis in the time domain
- Authors: Frieslaar, Ibraheem
- Date: 2019
- Subjects: Computer security , Data encryption (Computer science) , Noise generators (Electronics)
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/71152 , vital:29790
- Description: This research is the first of its kind to investigate the utilisation of a multi-threading software-based countermeasure to mitigate Side Channel Analysis (SCA) attacks, with a particular focus on the AES-128 cryptographic algorithm. This investigation is novel, as there has not been a software-based countermeasure relying on multi-threading to our knowledge. The research has been tested on the Atmel microcontrollers, as well as a more fully featured system in the form of the popular Raspberry Pi that utilises the ARM7 processor. The main contributions of this research is the introduction of a multi-threading software based countermeasure used to mitigate SCA attacks on both an embedded device and a Raspberry Pi. These threads are comprised of various mathematical operations which are utilised to generate electromagnetic (EM) noise resulting in the obfuscation of the execution of the AES-128 algorithm. A novel EM noise generator known as the FRIES noise generator is implemented to obfuscate data captured in the EM field. FRIES comprises of hiding the execution of AES-128 algorithm within the EM noise generated by the 512 Secure Hash Algorithm (SHA) from the libcrypto++ and OpenSSL libraries. In order to evaluate the proposed countermeasure, a novel attack methodology was developed where the entire secret AES-128 encryption key was recovered from a Raspberry Pi, which has not been achieved before. The FRIES noise generator was pitted against this new attack vector and other known noise generators. The results exhibited that the FRIES noise generator withstood this attack whilst other existing techniques still leaked out secret information. The visual location of the AES-128 encryption algorithm in the EM spectrum and key recovery was prevented. These results demonstrated that the proposed multi-threading software based countermeasure was able to be resistant to existing and new forms of attacks, thus verifying that a multi-threading software based countermeasure can serve to mitigate SCA attacks.
- Full Text:
- Date Issued: 2019
- Authors: Frieslaar, Ibraheem
- Date: 2019
- Subjects: Computer security , Data encryption (Computer science) , Noise generators (Electronics)
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/71152 , vital:29790
- Description: This research is the first of its kind to investigate the utilisation of a multi-threading software-based countermeasure to mitigate Side Channel Analysis (SCA) attacks, with a particular focus on the AES-128 cryptographic algorithm. This investigation is novel, as there has not been a software-based countermeasure relying on multi-threading to our knowledge. The research has been tested on the Atmel microcontrollers, as well as a more fully featured system in the form of the popular Raspberry Pi that utilises the ARM7 processor. The main contributions of this research is the introduction of a multi-threading software based countermeasure used to mitigate SCA attacks on both an embedded device and a Raspberry Pi. These threads are comprised of various mathematical operations which are utilised to generate electromagnetic (EM) noise resulting in the obfuscation of the execution of the AES-128 algorithm. A novel EM noise generator known as the FRIES noise generator is implemented to obfuscate data captured in the EM field. FRIES comprises of hiding the execution of AES-128 algorithm within the EM noise generated by the 512 Secure Hash Algorithm (SHA) from the libcrypto++ and OpenSSL libraries. In order to evaluate the proposed countermeasure, a novel attack methodology was developed where the entire secret AES-128 encryption key was recovered from a Raspberry Pi, which has not been achieved before. The FRIES noise generator was pitted against this new attack vector and other known noise generators. The results exhibited that the FRIES noise generator withstood this attack whilst other existing techniques still leaked out secret information. The visual location of the AES-128 encryption algorithm in the EM spectrum and key recovery was prevented. These results demonstrated that the proposed multi-threading software based countermeasure was able to be resistant to existing and new forms of attacks, thus verifying that a multi-threading software based countermeasure can serve to mitigate SCA attacks.
- Full Text:
- Date Issued: 2019
Network simulation for professional audio networks
- Authors: Otten, Fred
- Date: 2015
- Subjects: Sound engineers , Ethernet (Local area network system) , Computer networks , Computer simulation
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4713 , http://hdl.handle.net/10962/d1017935
- Description: Audio Engineers are required to design and deploy large multi-channel sound systems which meet a set of requirements and use networking technologies such as Firewire and Ethernet AVB. Bandwidth utilisation and parameter groupings are among the factors which need to be considered in these designs. An implementation of an extensible, generic simulation framework would allow audio engineers to easily compare protocols and networking technologies and get near real time responses with regards to bandwidth utilisation. Our hypothesis is that an application-level capability can be developed which uses a network simulation framework to enable this process and enhances the audio engineer’s experience of designing and configuring a network. This thesis presents a new, extensible simulation framework which can be utilised to simulate professional audio networks. This framework is utilised to develop an application - AudioNetSim - based on the requirements of an audio engineer. The thesis describes the AudioNetSim models and implementations for Ethernet AVB, Firewire and the AES- 64 control protocol. AudioNetSim enables bandwidth usage determination for any network configuration and connection scenario and is used to compare Firewire and Ethernet AVB bandwidth utilisation. It also applies graph theory to the circular join problem and provides a solution to detect circular joins.
- Full Text:
- Date Issued: 2015
- Authors: Otten, Fred
- Date: 2015
- Subjects: Sound engineers , Ethernet (Local area network system) , Computer networks , Computer simulation
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4713 , http://hdl.handle.net/10962/d1017935
- Description: Audio Engineers are required to design and deploy large multi-channel sound systems which meet a set of requirements and use networking technologies such as Firewire and Ethernet AVB. Bandwidth utilisation and parameter groupings are among the factors which need to be considered in these designs. An implementation of an extensible, generic simulation framework would allow audio engineers to easily compare protocols and networking technologies and get near real time responses with regards to bandwidth utilisation. Our hypothesis is that an application-level capability can be developed which uses a network simulation framework to enable this process and enhances the audio engineer’s experience of designing and configuring a network. This thesis presents a new, extensible simulation framework which can be utilised to simulate professional audio networks. This framework is utilised to develop an application - AudioNetSim - based on the requirements of an audio engineer. The thesis describes the AudioNetSim models and implementations for Ethernet AVB, Firewire and the AES- 64 control protocol. AudioNetSim enables bandwidth usage determination for any network configuration and connection scenario and is used to compare Firewire and Ethernet AVB bandwidth utilisation. It also applies graph theory to the circular join problem and provides a solution to detect circular joins.
- Full Text:
- Date Issued: 2015
Preimages for SHA-1
- Authors: Motara, Yusuf Moosa
- Date: 2018
- Subjects: Data encryption (Computer science) , Computer security -- Software , Hashing (Computer science) , Data compression (Computer science) , Preimage , Secure Hash Algorithm 1 (SHA-1)
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/57885 , vital:27004
- Description: This research explores the problem of finding a preimage — an input that, when passed through a particular function, will result in a pre-specified output — for the compression function of the SHA-1 cryptographic hash. This problem is much more difficult than the problem of finding a collision for a hash function, and preimage attacks for very few popular hash functions are known. The research begins by introducing the field and giving an overview of the existing work in the area. A thorough analysis of the compression function is made, resulting in alternative formulations for both parts of the function, and both statistical and theoretical tools to determine the difficulty of the SHA-1 preimage problem. Different representations (And- Inverter Graph, Binary Decision Diagram, Conjunctive Normal Form, Constraint Satisfaction form, and Disjunctive Normal Form) and associated tools to manipulate and/or analyse these representations are then applied and explored, and results are collected and interpreted. In conclusion, the SHA-1 preimage problem remains unsolved and insoluble for the foreseeable future. The primary issue is one of efficient representation; despite a promising theoretical difficulty, both the diffusion characteristics and the depth of the tree stand in the way of efficient search. Despite this, the research served to confirm and quantify the difficulty of the problem both theoretically, using Schaefer's Theorem, and practically, in the context of different representations.
- Full Text:
- Date Issued: 2018
- Authors: Motara, Yusuf Moosa
- Date: 2018
- Subjects: Data encryption (Computer science) , Computer security -- Software , Hashing (Computer science) , Data compression (Computer science) , Preimage , Secure Hash Algorithm 1 (SHA-1)
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/57885 , vital:27004
- Description: This research explores the problem of finding a preimage — an input that, when passed through a particular function, will result in a pre-specified output — for the compression function of the SHA-1 cryptographic hash. This problem is much more difficult than the problem of finding a collision for a hash function, and preimage attacks for very few popular hash functions are known. The research begins by introducing the field and giving an overview of the existing work in the area. A thorough analysis of the compression function is made, resulting in alternative formulations for both parts of the function, and both statistical and theoretical tools to determine the difficulty of the SHA-1 preimage problem. Different representations (And- Inverter Graph, Binary Decision Diagram, Conjunctive Normal Form, Constraint Satisfaction form, and Disjunctive Normal Form) and associated tools to manipulate and/or analyse these representations are then applied and explored, and results are collected and interpreted. In conclusion, the SHA-1 preimage problem remains unsolved and insoluble for the foreseeable future. The primary issue is one of efficient representation; despite a promising theoretical difficulty, both the diffusion characteristics and the depth of the tree stand in the way of efficient search. Despite this, the research served to confirm and quantify the difficulty of the problem both theoretically, using Schaefer's Theorem, and practically, in the context of different representations.
- Full Text:
- Date Issued: 2018
Behavioural model debugging in Linda
- Authors: Sewry, David Andrew
- Date: 1994
- Subjects: LINDA (Computer system) Debugging in computer science
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4674 , http://hdl.handle.net/10962/d1006697
- Description: This thesis investigates event-based behavioural model debugging in Linda. A study is presented of the Linda parallel programming paradigm, its amenability to debugging, and a model for debugging Linda programs using Milner's CCS. In support of the construction of expected behaviour models, a Linda program specification language is proposed. A behaviour recognition engine that is based on such specifications is also discussed. It is shown that Linda's distinctive characteristics make it amenable to debugging without the usual problems associated with paraUel debuggers. Furthermore, it is shown that a behavioural model debugger, based on the proposed specification language, effectively exploits the debugging opportunity. The ideas developed in the thesis are demonstrated in an experimental Modula-2 Linda system.
- Full Text:
- Date Issued: 1994
- Authors: Sewry, David Andrew
- Date: 1994
- Subjects: LINDA (Computer system) Debugging in computer science
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4674 , http://hdl.handle.net/10962/d1006697
- Description: This thesis investigates event-based behavioural model debugging in Linda. A study is presented of the Linda parallel programming paradigm, its amenability to debugging, and a model for debugging Linda programs using Milner's CCS. In support of the construction of expected behaviour models, a Linda program specification language is proposed. A behaviour recognition engine that is based on such specifications is also discussed. It is shown that Linda's distinctive characteristics make it amenable to debugging without the usual problems associated with paraUel debuggers. Furthermore, it is shown that a behavioural model debugger, based on the proposed specification language, effectively exploits the debugging opportunity. The ideas developed in the thesis are demonstrated in an experimental Modula-2 Linda system.
- Full Text:
- Date Issued: 1994
Grouping complex systems for classification and parallel simulation
- Authors: Ikram, Ismail Mohamed
- Date: 1997
- Subjects: Digital computer simulation
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4662 , http://hdl.handle.net/10962/d1006665
- Description: This thesis is concerned with grouping complex systems by means of concurrent model, in order to aid in (i) formulation of classifications and (ii) induction of parallel simulation programs. It observes, and seeks f~ furmalize _ and then exploit, the strong structural resemblance between complex systems and occam programs. The thesis hypothesizes that groups of complex systems may be discriminated according to shared structural and behavioural characteristics. Such an analysis of the complex systems domain may be performed in the abstract with the aid of a model for capturing interesting features of complex systems. The resulting groups would form a classification of complex systems. An additional hypothesis is that, insofar as the model is able to capture sufficient . programmatic information, these groups may be used to define, automatically, algorithmic skeletons for the concurrent simulation of complex systems. In order to test these hypotheses, a specification model and an accompanying formal notation are developed. The model expresses properties of complex systems in a mixture of object-oriented and process-oriented styles .. The model is then used as the basis for performing both classification and automatic induction of parallel simulation programs. The thesis takes the view that specification models should not be overly complex, especially if the specifications are meant to be executable. Therefore the requirement for explicit consideration of concurrency on the part of specifiers is minimized. The thesis formulates specifications of classes of cellular automata and neural networks according to the proposed model. Procedures for verificati6If - and induction of parallel simulation programs are also included.
- Full Text:
- Date Issued: 1997
- Authors: Ikram, Ismail Mohamed
- Date: 1997
- Subjects: Digital computer simulation
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4662 , http://hdl.handle.net/10962/d1006665
- Description: This thesis is concerned with grouping complex systems by means of concurrent model, in order to aid in (i) formulation of classifications and (ii) induction of parallel simulation programs. It observes, and seeks f~ furmalize _ and then exploit, the strong structural resemblance between complex systems and occam programs. The thesis hypothesizes that groups of complex systems may be discriminated according to shared structural and behavioural characteristics. Such an analysis of the complex systems domain may be performed in the abstract with the aid of a model for capturing interesting features of complex systems. The resulting groups would form a classification of complex systems. An additional hypothesis is that, insofar as the model is able to capture sufficient . programmatic information, these groups may be used to define, automatically, algorithmic skeletons for the concurrent simulation of complex systems. In order to test these hypotheses, a specification model and an accompanying formal notation are developed. The model expresses properties of complex systems in a mixture of object-oriented and process-oriented styles .. The model is then used as the basis for performing both classification and automatic induction of parallel simulation programs. The thesis takes the view that specification models should not be overly complex, especially if the specifications are meant to be executable. Therefore the requirement for explicit consideration of concurrency on the part of specifiers is minimized. The thesis formulates specifications of classes of cellular automata and neural networks according to the proposed model. Procedures for verificati6If - and induction of parallel simulation programs are also included.
- Full Text:
- Date Issued: 1997
The development of a discovery and control environment for networked audio devices based on a study of current audio control protocols
- Authors: Eales, Andrew Arnold
- Date: 2016
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/539 , vital:19968
- Description: This dissertation develops a standard device model for networked audio devices and introduces a novel discovery and control environment that uses the developed device model. The proposed standard device model is derived from a study of current audio control protocols. Both the functional capabilities and design principles of audio control protocols are investigated with an emphasis on Open Sound Control, SNMP and IEC-62379, AES64, CopperLan and UPnP. An abstract model of networked audio devices is developed, and the model is implemented in each of the previously mentioned control protocols. This model is also used within a novel discovery and control environment designed around a distributed associative memory termed an object space. This environment challenges the accepted notions of the functionality provided by a control protocol. The study concludes by comparing the salient features of the different control protocols encountered in this study. Different approaches to control protocol design are considered, and several design heuristics for control protocols are proposed.
- Full Text:
- Date Issued: 2016
- Authors: Eales, Andrew Arnold
- Date: 2016
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/539 , vital:19968
- Description: This dissertation develops a standard device model for networked audio devices and introduces a novel discovery and control environment that uses the developed device model. The proposed standard device model is derived from a study of current audio control protocols. Both the functional capabilities and design principles of audio control protocols are investigated with an emphasis on Open Sound Control, SNMP and IEC-62379, AES64, CopperLan and UPnP. An abstract model of networked audio devices is developed, and the model is implemented in each of the previously mentioned control protocols. This model is also used within a novel discovery and control environment designed around a distributed associative memory termed an object space. This environment challenges the accepted notions of the functionality provided by a control protocol. The study concludes by comparing the salient features of the different control protocols encountered in this study. Different approaches to control protocol design are considered, and several design heuristics for control protocols are proposed.
- Full Text:
- Date Issued: 2016
A networking approach to sharing music studio resources
- Authors: Foss, Richard John
- Date: 1996
- Subjects: MIDI (Standard) Computer sound processing Sound -- Recording and reproducing -- Digital techniques
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4659 , http://hdl.handle.net/10962/d1006660
- Description: This thesis investigates the extent to which networking technology can be used to provide remote workstation access to a pool of shared music studio resources. A pilot system is described in which MIDI messages, studio control data, and audio signals flow between the workstations and a studio server. A booking and timing facility avoids contention and allows for accurate reports of studio usage. The operation of the system has been evaluated in terms of its ability to satislY three fundamental goals, namely the remote, shared and centralized access to studio resources. Three essential network configurations have been identified, incorporating a mix of star and bus topologies, and their relative potential for satisfYing the fundamental goals has been highlighted.
- Full Text:
- Date Issued: 1996
- Authors: Foss, Richard John
- Date: 1996
- Subjects: MIDI (Standard) Computer sound processing Sound -- Recording and reproducing -- Digital techniques
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4659 , http://hdl.handle.net/10962/d1006660
- Description: This thesis investigates the extent to which networking technology can be used to provide remote workstation access to a pool of shared music studio resources. A pilot system is described in which MIDI messages, studio control data, and audio signals flow between the workstations and a studio server. A booking and timing facility avoids contention and allows for accurate reports of studio usage. The operation of the system has been evaluated in terms of its ability to satislY three fundamental goals, namely the remote, shared and centralized access to studio resources. Three essential network configurations have been identified, incorporating a mix of star and bus topologies, and their relative potential for satisfYing the fundamental goals has been highlighted.
- Full Text:
- Date Issued: 1996
Investigating combinations of feature extraction and classification for improved image-based multimodal biometric systems at the feature level
- Authors: Brown, Dane
- Date: 2018
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/63470 , vital:28414
- Description: Multimodal biometrics has become a popular means of overcoming the limitations of unimodal biometric systems. However, the rich information particular to the feature level is of a complex nature and leveraging its potential without overfitting a classifier is not well studied. This research investigates feature-classifier combinations on the fingerprint, face, palmprint, and iris modalities to effectively fuse their feature vectors for a complementary result. The effects of different feature-classifier combinations are thus isolated to identify novel or improved algorithms. A new face segmentation algorithm is shown to increase consistency in nominal and extreme scenarios. Moreover, two novel feature extraction techniques demonstrate better adaptation to dynamic lighting conditions, while reducing feature dimensionality to the benefit of classifiers. A comprehensive set of unimodal experiments are carried out to evaluate both verification and identification performance on a variety of datasets using four classifiers, namely Eigen, Fisher, Local Binary Pattern Histogram and linear Support Vector Machine on various feature extraction methods. The recognition performance of the proposed algorithms are shown to outperform the vast majority of related studies, when using the same dataset under the same test conditions. In the unimodal comparisons presented, the proposed approaches outperform existing systems even when given a handicap such as fewer training samples or data with a greater number of classes. A separate comprehensive set of experiments on feature fusion show that combining modality data provides a substantial increase in accuracy, with only a few exceptions that occur when differences in the image data quality of two modalities are substantial. However, when two poor quality datasets are fused, noticeable gains in recognition performance are realized when using the novel feature extraction approach. Finally, feature-fusion guidelines are proposed to provide the necessary insight to leverage the rich information effectively when fusing multiple biometric modalities at the feature level. These guidelines serve as the foundation to better understand and construct biometric systems that are effective in a variety of applications.
- Full Text:
- Date Issued: 2018
- Authors: Brown, Dane
- Date: 2018
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/63470 , vital:28414
- Description: Multimodal biometrics has become a popular means of overcoming the limitations of unimodal biometric systems. However, the rich information particular to the feature level is of a complex nature and leveraging its potential without overfitting a classifier is not well studied. This research investigates feature-classifier combinations on the fingerprint, face, palmprint, and iris modalities to effectively fuse their feature vectors for a complementary result. The effects of different feature-classifier combinations are thus isolated to identify novel or improved algorithms. A new face segmentation algorithm is shown to increase consistency in nominal and extreme scenarios. Moreover, two novel feature extraction techniques demonstrate better adaptation to dynamic lighting conditions, while reducing feature dimensionality to the benefit of classifiers. A comprehensive set of unimodal experiments are carried out to evaluate both verification and identification performance on a variety of datasets using four classifiers, namely Eigen, Fisher, Local Binary Pattern Histogram and linear Support Vector Machine on various feature extraction methods. The recognition performance of the proposed algorithms are shown to outperform the vast majority of related studies, when using the same dataset under the same test conditions. In the unimodal comparisons presented, the proposed approaches outperform existing systems even when given a handicap such as fewer training samples or data with a greater number of classes. A separate comprehensive set of experiments on feature fusion show that combining modality data provides a substantial increase in accuracy, with only a few exceptions that occur when differences in the image data quality of two modalities are substantial. However, when two poor quality datasets are fused, noticeable gains in recognition performance are realized when using the novel feature extraction approach. Finally, feature-fusion guidelines are proposed to provide the necessary insight to leverage the rich information effectively when fusing multiple biometric modalities at the feature level. These guidelines serve as the foundation to better understand and construct biometric systems that are effective in a variety of applications.
- Full Text:
- Date Issued: 2018
An investigation into XSets of primitive behaviours for emergent behaviour in stigmergic and message passing antlike agents
- Authors: Chibaya, Colin
- Date: 2014
- Subjects: Ants -- Behavior -- Computer programs , Insects -- Behavior -- Computer programs , Ant communities -- Behavior , Insect societies
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4698 , http://hdl.handle.net/10962/d1012965
- Description: Ants are fascinating creatures - not so much because they are intelligent on their own, but because as a group they display compelling emergent behaviour (the extent to which one observes features in a swarm which cannot be traced back to the actions of swarm members). What does each swarm member do which allows deliberate engineering of emergent behaviour? We investigate the development of a language for programming swarms of ant agents towards desired emergent behaviour. Five aspects of stigmergic (pheromone sensitive computational devices in which a non-symbolic form of communication that is indirectly mediated via the environment arises) and message passing ant agents (computational devices which rely on implicit communication spaces in which direction vectors are shared one-on-one) are studied. First, we investigate the primitive behaviours which characterize ant agents' discrete actions at individual levels. Ten such primitive behaviours are identified as candidate building blocks of the ant agent language sought. We then study mechanisms in which primitive behaviours are put together into XSets (collection of primitive behaviours, parameter values, and meta information which spells out how and when primitive behaviours are used). Various permutations of XSets are possible which define the search space for best performer XSets for particular tasks. Genetic programming principles are proposed as a search strategy for best performer XSets that would allow particular emergent behaviour to occur. XSets in the search space are evolved over various genetic generations and tested for abilities to allow path finding (as proof of concept). XSets are ranked according to the indices of merit (fitness measures which indicate how well XSets allow particular emergent behaviour to occur) they achieve. Best performer XSets for the path finding task are identifed and reported. We validate the results yield when best performer XSets are used with regard to normality, correlation, similarities in variation, and similarities between mean performances over time. Commonly, the simulation results yield pass most statistical tests. The last aspect we study is the application of best performer XSets to different problem tasks. Five experiments are administered in this regard. The first experiment assesses XSets' abilities to allow multiple targets location (ant agents' abilities to locate continuous regions of targets), and found out that best performer XSets are problem independent. However both categories of XSets are sensitive to changes in agent density. We test the influences of individual primitive behaviours and the effects of the sequences of primitive behaviours to the indices of merit of XSets and found out that most primitive behaviours are indispensable, especially when specific sequences are prescribed. The effects of pheromone dissipation to the indices of merit of stigmergic XSets are also scrutinized. Precisely, dissipation is not causal. Rather, it enhances convergence. Overall, this work successfully identify the discrete primitive behaviours of stigmergic and message passing ant-like devices. It successfully put these primitive behaviours together into XSets which characterize a language for programming ant-like devices towards desired emergent behaviour. This XSets approach is a new ant language representation with which a wider domain of emergent tasks can be resolved.
- Full Text:
- Date Issued: 2014
- Authors: Chibaya, Colin
- Date: 2014
- Subjects: Ants -- Behavior -- Computer programs , Insects -- Behavior -- Computer programs , Ant communities -- Behavior , Insect societies
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4698 , http://hdl.handle.net/10962/d1012965
- Description: Ants are fascinating creatures - not so much because they are intelligent on their own, but because as a group they display compelling emergent behaviour (the extent to which one observes features in a swarm which cannot be traced back to the actions of swarm members). What does each swarm member do which allows deliberate engineering of emergent behaviour? We investigate the development of a language for programming swarms of ant agents towards desired emergent behaviour. Five aspects of stigmergic (pheromone sensitive computational devices in which a non-symbolic form of communication that is indirectly mediated via the environment arises) and message passing ant agents (computational devices which rely on implicit communication spaces in which direction vectors are shared one-on-one) are studied. First, we investigate the primitive behaviours which characterize ant agents' discrete actions at individual levels. Ten such primitive behaviours are identified as candidate building blocks of the ant agent language sought. We then study mechanisms in which primitive behaviours are put together into XSets (collection of primitive behaviours, parameter values, and meta information which spells out how and when primitive behaviours are used). Various permutations of XSets are possible which define the search space for best performer XSets for particular tasks. Genetic programming principles are proposed as a search strategy for best performer XSets that would allow particular emergent behaviour to occur. XSets in the search space are evolved over various genetic generations and tested for abilities to allow path finding (as proof of concept). XSets are ranked according to the indices of merit (fitness measures which indicate how well XSets allow particular emergent behaviour to occur) they achieve. Best performer XSets for the path finding task are identifed and reported. We validate the results yield when best performer XSets are used with regard to normality, correlation, similarities in variation, and similarities between mean performances over time. Commonly, the simulation results yield pass most statistical tests. The last aspect we study is the application of best performer XSets to different problem tasks. Five experiments are administered in this regard. The first experiment assesses XSets' abilities to allow multiple targets location (ant agents' abilities to locate continuous regions of targets), and found out that best performer XSets are problem independent. However both categories of XSets are sensitive to changes in agent density. We test the influences of individual primitive behaviours and the effects of the sequences of primitive behaviours to the indices of merit of XSets and found out that most primitive behaviours are indispensable, especially when specific sequences are prescribed. The effects of pheromone dissipation to the indices of merit of stigmergic XSets are also scrutinized. Precisely, dissipation is not causal. Rather, it enhances convergence. Overall, this work successfully identify the discrete primitive behaviours of stigmergic and message passing ant-like devices. It successfully put these primitive behaviours together into XSets which characterize a language for programming ant-like devices towards desired emergent behaviour. This XSets approach is a new ant language representation with which a wider domain of emergent tasks can be resolved.
- Full Text:
- Date Issued: 2014